Restraining containers in storage racks and the like can be particularly problematic when the racks are onboard moving vehicles. When being transported by aircraft, the racks can be subjected to considerable forces, e.g. 3-5 G. Usually, a large number of ropes, etc are required to tie the items in this situation, but this takes up a considerable amount of time and means that removing the containers is also an awkward and time-consuming process. This is clearly disadvantageous when the contents need to be unloaded quickly. It can also be difficult to correctly load and unload items from a container that is on an uneven (or moving) surface. The rack may slope and so the rails upon which the container rests can be mis-aligned vertically.